Update kube-scheduler.md

Fix grammar typo

content/en/docs/concepts/scheduling/kube-scheduler.md

@@ -34,7 +34,7 @@ is the default scheduler for Kubernetes and runs as part of the
 kube-scheduler is designed so that, if you want and need to, you can
 write your own scheduling component and use that instead.
 
-For every newly created pods or other unscheduled pods, kube-scheduler
+For every newly created pod or other unscheduled pods, kube-scheduler
 selects a optimal node for them to run on.  However, every container in
 pods has different requirements for resources and every pod also has
 different requirements. Therefore, existing nodes need to be filtered